bio212

DNA Technology

Recombinant DNA and

Genetic Engineering

Outline

1. Key Concepts

2. DNA Cloning

3. Genetic Engineering

4. Key Terms

5. Conclusions

Key Concepts


Genetic experiments have been
proceeding in nature for billions of years


Genetic changes are brought about by
Recombinant DNA technology


With technology, researchers can isolate,
cut, and splice together gene regions
from different species, and amplify the
number of copies

Key Concepts


Recombinant DNA technology depends on 3
activities

–
Cutting DNA into fragments

–
Insertion of fragments into cloning tools like plasmids

–
clone and identification of desired clone


Genetic engineering involves isolating,
modifying, and inserting genes back into the
same organism or into a different one


Social, ethical, legal, and ecological questions
are raised by the new technology

Glowing mice

Producing Restriction
Fragments


Restriction enzymes

–
Cut at specific nucleotide sequences

–
Some create “Sticky Ends”

–
DNA fragments cut with the same
restriction enzyme will base
-
pair to form
recombinant fragments


DNA ligase

–
Seals nicks where fragments base pair

Using a
restriction
enzyme and DNA
ligase to make
recombinant DNA

a. Restriction enzyme

cuts chromosomal or

cDNA

c. DNA or

cDNA

fragments


d. Plasmid

fragments

e. DNA fragments

and

modification

enzymes

are mixed

together

f. A collection of

recombinant

plasmids



g. Host cells able
to divide rapidly
take up
recombinant
plasmids


b. Same enzyme

cuts plasmid DNA

DNA Cloning and Genome (DNA) library

The original plasmid is called a

cloning vector

(taxi for delivering foreign DNA into a bacterium)

Human gene Cloning

Complementary DNA (cDNA)


Reverse
transcription

cDNA library

Polymerase Chain Reaction (PCR)

(any piece of DNA can be quickly amplified)


Heat DNA to unwind to single
strands


Add primers that base
-
pair with
ends



Cool mixture to promote base
-
pairing


DNA polymerase assembles
complementary sequences,
doubling number of identical
fragments


Repeat process over and over


Genetic engineering


The goal is to beneficially modifying traits
that the genes influence.

Bacteria


Genetically Engineered Bacteria

–
Insulin production

–
Growth hormone

–
Oil degraders

–
Pesticide control

Plant

Genetically
engineered cotton
plant having a gene
for herbicide
resistance.

Both had been
sprayed with a
weedkiller


Regenerating Plants from
Cultured Cells

Plant glows in
the dark owing
to a gene
transfer

Genetic Engineering of Animals


Insertion of gene into fertilized egg


Animals produce new products


Cloning

–
Dolly

Dolly and her first lamb

Applying the New Technology to
Humans


Human Genome Project


3.2 billion base pairs

–
99.9% of nucleotide sequence is same
for all humans

–
0.1% account for all genetic differences

DNA Sequencing

Genetic engineering

Recombination DNA

Biotechnology

Gene cloning

Restriction enzymes

cDNA

Cloning vector

Stick ends

DNA ligase

PCR

Genomic library

Polymerase chain reaction

Human Genome Project

In Conclusion


Nature conducts her own genetic engineering
experiments


Recombinant DNA technology allows the isolation,
cutting, and splicing of gene regions



Restriction enzymes and DNA ligase allow new DNA to
be inserted into plasmids


DNA libraries are collections of DNA fragments


Amplification can be done using bacteria or yeast or by
PCR


In Conclusion


Genetic engineering involves the isolation,
modification, and insertion of genes


Recombinant DNA technology and genetic
engineering have potential research and
applications in medicine, agriculture, and
industry